Dive for a while, and you’re bound to run into a fish named after Commerson. But just who is Commerson, and why is so much named after him?

Philibert Commerson was a French naturalist from the mid-18th century. He is best known—especially for fish lovers—for circumnavigating the globe with Louise Antoine de Bougainville from 1766-1769. An astute observer, Commerson discovered many species of fish, as well as trees and plants.

• Commerson’s dolphin. We saw this species in our guide to dolphins article. Commerson discovered this dolphin in the Strait of Magellan.
• Commerson’s frogfish. As with many circumnavigators, the Pacific was a great opportunity for European exploration, so this species of frogfish was particularly exciting. Look for it around the islands of Hawaii.
• Common sucker. This sucker fish’s genus name is Catostomus Commerson, and is sometimes called a sand sucker. It’s fairly common in the United States.
• Commerson’s anchovy. Yup, he even has his own anchovy. These little guys live around Australia and Southern Asia.
• Commerson’s glassy. This tiny fish can be found off the coast of Africa, where Commerson spent the end of his life.
• Commerson’s sole. This fish has hardly any distinguishable fins. It lives in the mud in brackish waters in the Indo-West Pacific.
• Commerson’s mackerel. A type of Spanish mackerel in the west Pacific.
• Commerson’s sea pike. This is basically another name for a Great Barracuda.

Quite a list, and I’m not even sure that it’s exhaustive. If anything, it shows that it pays off to be the first to go somewhere with an observant eye.

On the return trip to France in 1769, Commerson opted to stay behind on the islands of Mauritius and Madagascar. He died 4 years later.

Photo by prilfish

Sea bass is part of the grouper family, which we’ve already covered. There are many types, including black sea bass, Asian seabass, European seabass, and the giant sea bass.

Physical description

Being from the same family, it is not surprising that sea bass share grouper’s strong “fishy” appearance often associated with fish we eat.

The dorsal fins of the sea bass are one long continuous fin, rather than two separate sets of spines. The caudal and pectoral fins are rounded.

They have large, fleshy lips. It is also a tall fish, with a high back, moderately pointed snout, flat topped head, and eyes set high.

Color is inconsistent in this family, but generally lies in the dark range: browns, black, and dark blues.

Size can also vary widely based on specific species, with most in the 1-2 feet range. However, the giant sea bass has been reported to grow up to 2.5 m (8.2 feet) and weighing as much as 255 kg (562 lbs)! Quoting the wikipedia article, “Due its size and carnivorous nature, it can pose some threat to humans.” Whoa!

Geography and habitat

Sea bass are found all over the world, in all waters. Most areas have a few species that are specific to those waters.

They like to hang around the sea floor, especially near rocks, man-made reefs, wrecks, and the like.

Conservation

The Environmental Defense Fund lists the Chilean sea bass, a.k.a. toothfish, as an “eco-worst choice” seafood, and suggests avoiding. Basically everything that can be wrong is wrong: they are overfished, fished illegally, other animals are killed during fishing, and they have high levels of mercury. Best to avoid Chilean sea bass.

Efforts have been underway for a while to regrow the black sea bass populations, so they are listed as “Eco-OK” to eat.

Further reading

Wikipedia
gma.org
Britannica Online Encyclopedia

Photo by Mike Johnson

Photo by docbaty

If you’ve taken a Fish Identification specialty, you’ve probably heard of REEF, the Reef Environmental Education Foundation. REEF tackles an interesting problem, understanding and protecting marine life, by allowing recreational divers the opportunity to get involved.

REEF was founded in 1990 when its founders realized the increasing threats faced by marine populations. Despite these threats, the scientific community lacked the resources to collect the data needed to combat the problem. By tapping into recreational divers’ affinity for sea life, REEF vastly increases the available amount of resources.

The primary way in which divers help is by surveying fish populations. During a regular dive, the diver simply takes notes on the types and numbers of fish seen. This data is then sent in to REEF, where it is used to increase the knowledge base needed by marine scientists, conservationists, and resource managers.

Note that REEF currently only operates in the coastal regions of North and Central America, the Caribbean, and Hawaii.

Getting started

Interested in getting involved? The first step is to become a REEF member. Membership is free and includes a unique ID number, website login, and a newsletter subscription (annual by mail, monthly by email) that keeps you abreast of developments in the REEF community.

Next, you’ll need to brush up on your fish identification skills. You’re not expected to know every fish, but being able to identify a decent number of fish makes the data you collect all the more useful. See The Diving Blog’s fish identification series for a continual source of learning.

There are a few ways besides self study to learn fish. There are fish identification specialty courses. These will cover the basics of fish families and may involve a few dives to try it out. There are fish identification seminars at REEF field stations—check the website for more information. REEF staff also organize field-survey trips as a hands-on method of learning.

Collecting data

Once you’re ready to collect data, there’s not much left to do. You are welcome to join the aforementioned field-survey trips or survey fish during a dive of your own.

During a dive, REEF recommends what is called the Roving Diver Technique (RDT). This technique is based around the idea that you don’t modify your dive in any way, but simply mark types and quantities of fish as they are encountered.

This information is collected on specialized slates with waterproof forms specific to the region being surveyed. On it, you will mark the species of fish seen and the abundance: “Single” for one fish, “Few” for two to 10, “Many” for 11 to 100, and “Abundant” for over 100.

When you don’t recognize a species, you can sketch it on the slate, taking note of distinguishing features.

Afterwards, you’ll transfer this data to a special scanform (freely available from the REEF store) and send it to REEF headquarters, where it is catalogued and made part of the database.

For fun, REEF has levels of certification based on number of surveys completed and various quizzes that can be taken.

I have yet to collect a survey, but it’s something I’d be interested in doing. If you’re looking to add some purpose to your diving, or if you feel like things have stagnated for you, this could be an interesting way to renew your interest. Sign up and get some scanforms—you’re under no obligation to complete them. Try it out once and see how you like it. You may be surprised.

The ocean sunfish, or mola mola, as it is most often called, is a fascinating sea creature. Their odd appearance and enormous size makes them a popular attraction at aquariums around the world.

Physical description

Mola mola are big. Really big. In fact, it’s the heaviest known bony fish in the world. Sunfish, on average, weigh well over a ton (1,000 kg), and are almost 6 feet (2 m) in length. There have been sightings of mola mola over twice these sizes, though.

Sunfish look like some kind of freak accident. Their bodies resemble a lump of poorly molded clay with a fin on the top and bottom. The body is flattened vertically (imagine a vertical pancake).

The dorsal and anal fin are particularly large, make the entire fish as tall as it is long. It also has small, fan-shaped pectoral fins. The mola mola doesn’t have a proper caudal fin, and instead has a lumpy tail.

Geography and habitat

Sunfish live across the globe in tropical and temperate regions.

They can swim deep (up to 2,000 ft, or 600 m), and actually spend most of their lives at deep depths. This, combined with their presence mostly in open waters, makes them a rare sighting on dives. If you’ve ever seen one while scuba diving, consider yourself quite lucky.

Sunfish have an interesting behavior that is the source of their name. They will occasionally swim close to the surface and turn horizontal, exposing the large side of their body to the sun. This basking behavior is thought to “thermally charge” the fish in preparation for diving to deep, cold water.

Overall, very little is known about mola mola.

Further reading

Wikipedia
FishBase.org
Monterey Bay Aquarium

Photos by Ilse Reijs and Jan-Noud Hutten and Dan Hershman

In Part I one of this series we covered the more common kinds of dolphins. These included the common dolphin, the bottlenose, the right whale, and the killer whale (orca).

Today brings us to the less common families. They’re not necessarily endangered, but these families tend to be more localized to specific regions.

Humpback dolphin

Surprise, surprise. Humpback dolphins are distinguished by the noticeable hump along their backs. Additionally, they have an elongated dorsal fin.

The location of the humpback depends on the individual species. The Pacific humpback dolphin has a range throughout the Indo-Pacific region around China and Australia. The Indian humpback can be found in the Indian Ocean and along the eastern coast of Africa. The Atlantic dolphin lives along the western coast of northern Africa.

Spotted dolphin

Spotted dolphins are found in tropical and temperate climates across the globe. As usual, individual species are distinguished by their region. These include the Atlantic, spinner, and the pantropical spotted dolphins. The striped dolphin counts itself as a member of the spotted family (go figure).

Spotted dolphins are born spotless, and gradually develop spots as they get older. The family is sometimes also called bridled dolphins.

Tucuxi dolphin

The Tucuxi (pronounced “too-koo-shi”) is found along the eastern coast of South America and along the Amazon River basin. Despite this river habitat, they are classified as an oceanic dolphin.

Although they are in separate dolphin genera, Tucuxi strongly resemble the bottlenose dolphin, but maybe slightly smaller. They live in small pods of 10-15 dolphins and are thought to be quite active, like the bottlenose, often breaching out of the water.

Commerson’s, Chilean, Haviside’s, and Hector’s dolphin

These four species are classified into the same genus (cephalorhynchus, for you taxonomists out there). They are very similar physically, with small blunt noses and white patches.

Commerson’s is found near the southern tip of South America, Chilean along the western coast of South America, Haviside’s along the South African coast, Hector’s dolphin is found only in New Zealand.

For those keeping count, that’s 8 genera, out of 17. Keep an eye out in the future for a Part III.

The humphead wrasse is also called the Maori wrasse, Napoleon wrasse, and even Napoleon fish. You can call yourself lucky if you run into one of these relatively rare fish underwater.

Physical description

Humphead wrasse are the largest members of the wrasse family, with males reaching over 6 feet (2 meters) and females over 3 feet (1 meter) in length.

It has two distinguishing characteristics. The first, of course, is the large hump on its head, above the eyes. This protrusion becomes more noticeable as the fish ages. The other characteristics is the fish’s thick, Charles Laughton lips. Angelina Jolie wishes she had lips like these!

Female humpheads and juveniles are a red-orange color on top, and red-orange to white on their bellies. Juveniles may also be a light green color. Males, however, range in color from bright blue and green to purple.

Despite the abnormalities, humpheads have a normal, albeit larger, shaped wrasse body. This includes the fanned caudal fin.

Geography and habitat

Humphead wrasse are found in coral reefs in the Indo-Pacific oceans.

Adults maintain an open habitat at pretty much all depths, while juveniles like to maintain their privacy in seagrass or inside of dense coral.

Conservation

Humphead wrasse are declared rare by the World Wildlife Foundation, and in many countries they are protected.

Further reading

Wikipedia
World Wildlife Foundation
Dive the World

Photos by Electric Images

In a nutshell: big and ugly—that’s what today’s fish is. Grouper can be a familiar dive sighting, depending on where you dive. Even the sea bass is technically part of the grouper family, but we’ll be treating them separately.

Physical description

Grouper have oblong, stout bodies and a large mouth, probably not unlike some of your relatives. Typical lengths are over a meter, and can get to over 2 meters for the various giant varieties.

Their large mouths resemble a frown, contributing to the grouper’s unfriendly appearance. If you catch one with its mouth open, you will get a glimpse of its powerful gill muscles.

The pectoral fins have a fanlike appearance when in use. Combined with the fanned caudal fin, this is suggestive of the grouper’s slow, but strong swimming abilities.

There are over 60 species of grouper, so coloring varies wildly. Most often, though, grouper are a darkly colored brown, olive, or black with lighter splotches across their body.

Oh yeah, did I say that they’re big and ugly?

Geography and habitat

Grouper are found all over the world, with specific species local to different oceans. Their habitats can be a little more varied than most coral fish we cover here, including wanderings out to open water, due to their large size.

Grouper tend to be loner fish, and sometimes plant themselves beneath rocks and coral waiting for unsuspecting prey. At that time, they will use their strong gills to suck water, and the fish, into their mouths. Impressive.

Fishing

Grouper have become a popular sport fishing fish. Due to their size, I imagine they put up a good fight that fishermen find enjoyable.

Grouper are also eaten, although the environmental defense fund recommends caution. As with most larger fish, grouper have high mercury levels that could be dangerous to humans.

Further reading

Wikipedia
Florida Museum of Natural History

Grouper photo by love♡janine
Dusky grouper photo by Phillipe Guillaume
Potato grouper photo by Tim Sheerman-Chase

Barracuda actually encompasses a decently sized family of fish (sawtooth, Pacific, great, red, blackfin, and more). However, the differences are marginal, so we’ll cover them all together. Over time you should start to look up the species and study the differences. At the least, you should learn the species that live in the region where you dive.

Physical description

Barracuda have long, streamlined bodies that are rounded in the middle. Some species (like the great barracuda) can reach up to 1.8 meters (almost 6 feet!) in length, while most are a couple of feet long.

Most species have a distinctive underbite, which means their lower jaw appears to jut out, revealing a nasty set of teeth. Their teeth are fang-like, sharp, pointed, and all different sizes.

Barracuda can be anywhere from brownish to bluish gray on their upper body, with silvery sides leading to a white belly. Many species may have around 20 dark bars on their upper sides. If you see dark spots on the lower sides, you are probably looking at a great barracuda.

They have a rear dorsal fin paired with an anal fin right below it. They do have a forward dorsal fin, but it is usually flat and not visible. The caudal fin is moderately forked and suggestive of their swimming power.

Geography and habitat

Barracuda live in the tropical and subtropical regions across the globe. Most species spend their time near shore in coral reefs or mangroves. Some larger species are found in the open water, usually near the surface.

Barracuda tend to be solitary fish, hovering above reefs waiting to dash at prey. Younger barracuda, however, are sometimes seen in a group, called a battery.

Danger to humans

If you’ve ever caught sight of a barracuda watching you, it can be quite unnerving. In reality, they are of little danger to humans. It is true that wearing shiny jewelry and speared fish can attract the attention of a barracuda. Despite this, an attack is unlikely to be serious, at worse requiring stitches.

Be careful while spearfishing and avoid shiny objects and the chances of an attack are reduced to negligible.

Further reading

Wikipedia
Florida Museum of Natural History

Photo by JennyHuang